Terminologia Embryologica, in accordance with universal convention, deals with the entire period up to birth only in the human. It covers all of intra-uterine ontogeny and also a few key features of postnatal development. There are two principal parts. The first covers the pure terms, naming a structure or a developmental event. This covers the development of the early embryo as a whole, and is followed by sections on the individual systems. The arrangement of the terms follows the developmental sequence as closely as possible. Where this was not appropriate, as with lists of anomalies, terms were arranged alphabetically in Latin. The second part is chronological; it relates to the temporal sequence, and indicates new or especially conspicuous features at particular times. This encompasses the Carnegie Stages for the embryonic period and in addition identifies key features at individual points in the fetal period. In this part some items are not, sensu strictu, terms; instead they define succinctly a conspicuous feature or an event specific for the time.